Method for prevention and treatment of Escherichia coli infections using a bacteriophage with broad antibacterial spectrum against Escherichia coli

ABSTRACT

The present invention relates to a composition comprising the bacteriophage EK88P-1 isolated from the nature and having a broad antibacterial spectrum against  E. coli  as an active ingredient, and a method for preventing and treating  E. coli  infections using the said composition. The bacteriophage EK88P-1, the active ingredient of the composition of the present invention, has a broad antibacterial spectrum against  E. coli  and has the genome characteristically composed of the partial nucleotide sequences represented by SEQ ID NO: 1 to SEQ ID NO: 25, and also characterized by the bacteriophage belonging to the Myoviridae family according to the morphology that is composed of the major structural proteins in the sizes of approximately 49 kDa, 53 kDa, 94 kDa, and 103 kDa.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a composition usable for the prevention and treatment of E. coli infections which comprises a bacteriophage isolated from the nature and having a broad antibacterial spectrum against E. coli, and a method for preventing and treating E. coli infections using the same. More precisely, the present invention relates to a bacteriophage comprising the partial nucleotide sequences represented by SEQ ID NO: 1 to SEQ ID NO: 25, a composition for the prevention and treatment of E. coli infections comprising the said bacteriophage as an active ingredient, and a method for preventing and treating E. coli infections using the said composition.

2. Description of the Related Art

E. coli is Gram-negative intestinal bacteria belonging to bacillus. Most of E. coli are residential flora which means they are not pathogenic bacteria, yet. But, E. coli O157:H7 or ETEC (enterotoxigenic E. coli) are pathogenic bacteria that cause food poisoning in human or diarrhea in animals such as cow, pig, and goat, etc. Pathogenic E. coli can produce heat-labile enterotoxin (LT) that loses its activity when it is heated at 60° C. for 10 minutes, or heat-stable enterotoxin (ST) that exhibits resistance against heat and is stable at 100° C. upto 30 minutes.

Among the pathogenic E. coli, ETEC strains have been an issue that cause serious problems in livestock industry, particularly they cause diarrhea in newborn piglets or weaning pigs. Particularly, E. coli K88 strains, E. coli K99 strains, E. coli 987P strains, and E. coli F41 strains are known as the major enterotoxigenic E. coli types.

Considering a significant damage in livestock industry by such E. coli, it is urgently requested to develop a method for preventing or treating E. coli infections. A variety of antibiotics have been used to prevent or treat such pathogenic E. coli infections. However, according to the recent rise of antibiotic-resistant bacteria, an efficient alternative is urgently requested.

Recently, the use of bacteriophages has drawn our attention as a new way of treating bacterial infections. Particularly, the reason of our high interest in bacteriophages is because bacteriophage-based treatment is a nature-friendly method. Bacteriophages are an extremely small microorganism that infects bacteria, which are called phage in short. Once bacteriophage infects bacteria, the bacteriophage is proliferated in the inside of the bacterial cell. After full proliferation, the progenies destroy the bacterial cell wall to escape from the host, suggesting that the bacteriophage has bacteria killing ability. The bacteriophage infection is characterized by high specificity, so that a certain bacteriophage infects only a specific bacterium. That is, the bacterium that can be infected by certain bacteriophage is limited, suggesting that bacteriophage can kill only a specific bacterium and cannot harm other bacteria.

Bacteriophage was first found out by an English bacteriologist Twort in 1915 when he noticed that Micrococcus colonies melted and became transparent by something unknown. In 1917, a French bacteriologist d'Herelle found out that Shigella disentriae in the filtrate of dysentery patient feces melted by something, and further studied about this phenomenon. As a result, he identified bacteriophage independently, and named it as bacteriophage which means a bacteria killer. Since then, bacteriophages specifically acting against such pathogenic bacteria as Shigella, Salmonella typhi, and Vibrio cholerae have been continuously identified.

Owing to the unique capability of bacteriophage to kill bacteria, bacteriophages have been studied and anticipated as a method to treat bacterial infections. However, after penicillin was found by Fleming, studies on bacteriophages had been only continued in some of Eastern European countries and the former Soviet Union because of the universalization of antibiotics. After the year of 2000, the merit of the conventional antibiotics faded because of the increase of antibiotic-resistant bacteria. So, bacteriophages are once again spotlighted as a new anti-bacterial agent that can replace the conventional antibiotics.

According to the recent regulation of use of antibiotics by the government, the interest on bacteriophages increases more and more.

Thus, the present inventors tried to develop a composition usable for the prevention or treatment of E. coli infections by using a bacteriophage isolated from the nature and displayed a broad antibacterial spectrum against E. coli strains including E. coli K88 strains, and further tried to develop a method for preventing or treating E. coli infections using the said composition. As a result, the inventors succeeded in isolating an effective bacteriophage from the nature that displayed a broad antibacterial spectrum against E. coli strains and identified the partial nucleotide sequences of the genome of the isolated bacteriophage that could distinguish the isolated bacteriophage from previously reported bacteriophages. Based on that, the present inventors developed a composition comprising the isolated bacteriophage as an active ingredient and further confirmed that this composition could be efficiently used for the prevention and treatment of E. coli infections, leading to the completion of this present invention.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a novel bacteriophage that has a broad antibacterial spectrum against various E. coli strains including E. coli K88 strains.

It is another object of the present invention to provide a composition for preventing E. coli infections comprising the isolated bacteriophage having a broad antibacterial spectrum against various E. coli strains including E. coli K88 strains as an active ingredient, and a method for preventing E. coli infections using the said composition.

It is another object of the present invention to provide a composition for treating E. coli infections comprising the isolated bacteriophage having a broad antibacterial spectrum against various E. coli strains including E. coli K88 strains as an active ingredient, and a method for treating E. coli infections using the said composition.

It is further an object of the present invention to provide a disinfectant for the prevention and treatment of E. coli infections using the said composition.

It is also an object of the present invention to provide a drinking water additive for the prevention and treatment of E. coli infections using the said composition.

It is also an object of the present invention to provide a feed additive for the prevention and treatment of E. coli infections using the said composition.

To achieve the above objects, the present invention provides a composition comprising the bacteriophage isolated from the nature and displayed a broad antibacterial spectrum against various E. coli strains including E. coli K88 strains as an active ingredient, and a method for preventing and treating E. coli infections using the said composition.

The isolated bacteriophage included in the composition of the present invention as an active ingredient is the bacteriophage EK88P-1 that characteristically displays a broad antibacterial spectrum against various E. coli strains including E. coli K88 strains and contains the partial nucleotide sequences represented by SEQ ID NO: 1 to SEQ ID NO: 25. The bacteriophage EK88P-1 isolated by the present inventors was deposited at Korean Collection for Type Cultures, Korea Research Institute of Bioscience and Biotechnology in Apr. 10, 2014 (Accession No: KCTC 12574BP).

The present invention also provides a disinfectant, a drinking water additive, and a feed additive for the prevention or treatment of E. coli infections.

Since the bacteriophage EK88P-1 included in the composition of the present invention displays a broad antibacterial spectrum against various E. coli strains including E. coli K88 strains, it is regarded as to be effective in preventing or treating various diseases caused by various E. coli strains including E. coli K88 strains. Therefore, the composition of the present invention can be utilized for the prevention and treatment of diseases caused by various E. coli strains including E. coli K88 strains. The diseases caused by various E. coli strains including E. coli K88 strains herein indicate all the symptoms accompanied by E. coli infections including E. coli K88 infections, such as death, diarrhea, and growth retardation, etc.

In this description, the term “treatment” or “treat” indicates (i) to suppress the diseases caused by various E. coli strains including E. coli K88 strains; and (ii) to relieve the diseases caused by various E. coli strains including E. coli K88 strains.

In this description, the term “isolation” or “isolated” indicates all the actions to separate the bacteriophage by using diverse experimental techniques and to secure the characteristics that can distinguish this bacteriophage from others, and further includes the action of proliferating the bacteriophage via bioengineering techniques so as to make it useful.

The bacteriophage of the present invention includes the bacteriophage EK88P-1 and its variants. The “variants” herein indicate the bacteriophages that have minor variations in genomic sequence or polypeptide coding genetic information but have the equivalent genotypic and phenotypic characteristics as the bacteriophage EK88P-1 of the present invention. The said variants include polymorphic variants as well. It is preferred for those variants to have the same or equivalent biological functions as the bacteriophage EK88P-1 of the present invention.

The pharmaceutically acceptable carrier included in the composition of the present invention is the one that is generally used for the preparation of a pharmaceutical formulation, which is exemplified by glucose, maltodextrin, lactose, dextrose, sucrose, sorbitol, mannitol, starch, acacia rubber, calcium phosphate, alginate, gelatin, calcium silcate, microcrystalline cellulose, polyvinyl pyrrolidone, cellulose, water, syrup, methylcellulose, methylhydroxybenzoate, propylhydroxybenzoate, talc, magnesium stearate, and mineral oil, but not always limited thereto. The composition of the present invention can additionally include lubricants, wetting agents, sweeteners, flavors, emulsifiers, suspending agents, and preservatives, in addition to the above ingredients.

In the composition of the present invention, the bacteriophage EK88P-1 or the variants thereof are included as an active ingredient. At this time, the bacteriophage EK88P-1 or the variants thereof are preferably included at the concentration of 1×10¹ pfu/ml˜1×10³⁰ pfu/ml or 1×10¹ pfu/g˜1×10³⁰ pfu/g, and more preferably at the concentration of 1×10⁴ pfu/ml˜1×10¹⁵ pfu/ml or 1×10⁴ pfu/g˜1×10¹⁵ pfu/g.

The composition of the present invention can be formulated by the method that can be performed by those in the art by using a pharmaceutically acceptable carrier and/or excipient in the form of unit dose or in a multi-dose container. The formulation can be in the form of solution, suspension or emulsion in oil or water-soluble medium, extract, powder, granule, tablet or capsule. At this time, a dispersing agent or a stabilizer can be additionally included.

The composition of the present invention can be prepared as a disinfectant, a drinking water additive, or a feed additive according to the purpose of use, but not always limited thereto.

Advantageous Effect

The composition of the present invention and the method for preventing and treating various E. coli infections including E. coli K88 infections using the said composition have the advantage of high specificity to various E. coli strains including E. coli K88 strains, compared with the conventional methods based on the chemical materials including the conventional antibiotics. That means, the composition of the present invention can be used for preventing or treating various E. coli infections including E. coli K88 infections specifically without affecting other useful residential bacteria, and accordingly has fewer side effects. In general, when chemical materials such as antibiotics are used, the general residential bacteria are also damaged to weaken immunity in animals with carrying various side effects. In the meantime, the composition of the present invention uses the bacteriophage isolated from the nature as an active ingredient, so that it is very nature-friendly.

BRIEF DESCRIPTION OF THE DRAWINGS

The application of the preferred embodiments of the present invention is best understood with reference to the accompanying drawings, wherein:

FIG. 1 is an electron micrograph showing the morphology of the bacteriophage EK88P-1.

FIG. 2 is an electrophoresis photograph illustrating the result of one-dimensional electrophoresis performed for analysis of major structural protein of the bacteriophage EK88P-1, wherein lane M is the protein size marker and lane 1 is the protein sample of the bacteriophage EK88P-1. The major structural proteins are indicated by *.

FIG. 3 is a photograph illustrating the result of PCR using the genome of the bacteriophage EK88P-1 as a template, wherein lane 1 indicates the result of PCR with the primers respectively represented by SEQ ID NO: 26 and SEQ ID NO: 27, lane 2 indicates the result of PCR using the primers respectively represented by SEQ ID NO: 28 and SEQ ID NO: 29, lane 3 indicates the result of PCR using the primers respectively represented by SEQ ID NO: 30 and SEQ ID NO: 31, lane 4 indicates the result of PCR with the primers respectively represented by SEQ ID NO: 32 and SEQ ID NO: 33, lane 5 indicates the result of PCR with the primers respectively represented by SEQ ID NO: 34 and SEQ ID NO: 35, and lane M indicates the DNA size marker.

FIG. 4 is a photograph illustrating the capability of the bacteriophage EK88P-1 to kill E. coli cells. The clear zone in round shape is the plaque generated by lysis of E. coli cells on the dish.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Practical and presently preferred embodiments of the present invention are illustrative as shown in the following Examples.

However, it will be appreciated that those skilled in the art, on consideration of this disclosure, may make modifications and improvements within the spirit and scope of the present invention.

Example 1 Isolation of Bacteriophage Capable of Killing E. coli Cells

Samples were collected from the nature to screen the bacteriophage having the capability to kill E. coli cells. The E. coli strains used for the bacteriophage isolation herein were the one that had been isolated by the present inventors and identified as an E. coli K88 strain previously.

The isolation procedure of the bacteriophage is described in more detail hereinafter. The collected sample was added to the TSB (Tryptic Soy Broth) medium (pancreatic digest of casein, 17 g/L; papaic digest of soybean, 3 g/L; dextrose, 2.5 g/L; sodium chloride, 5 g/L; dipotassium phosphate, 2.5 g/L) inoculated with E. coli culture at the ratio of 1/1000, followed by shaking culture at 37° C. for 3˜4 hours. Upon completion of the culture, centrifugation was performed at 8,000 rpm for 20 minutes and supernatant was recovered. The recovered supernatant was inoculated with E. coli culture at the ratio of 1/1000, followed by shaking culture at 37° C. for 3˜4 hours. When the sample contained the effective bacteriophage, the above procedure was repeated total 5 times in order to increase the titer of the bacteriophage. After repeating the procedure 5 times, the culture solution proceeded to centrifugation at 8,000 rpm for 20 minutes and supernatant was recovered. The recovered supernatant was filtered by using a 0.45 μm filter. The obtained filtrate was used in spot assay for examining whether or not the bacteriophage that can kill E. coli cells was included therein.

Spot assay was performed as follows; TSB medium was inoculated with E. coli culture at the ratio of 1/1000, followed by shaking culture at 37° C. for overnight. 2 ml (OD₆₀₀=2.0) of the E. coli culture broth prepared above was spreaded on the TSA (Tryptic Soy Agar; pancreatic digest of casein, 17 g/L; papaic digest of soybean, 3 g/L; sodium chloride, 5 g/L; agar, 15 g/L) plate. The plate stood in a clean bench for 30 minutes to dry. After drying, 10 μl of the prepared filtrate was spotted directly onto the surface of the bacterial lawns and dried for about 30 minutes. Following drying, the plate was incubated at 37° C. for a day. Next day, the plate was examined for the formation of clear zones on the surface of the bacterial lawns. If a clear zone was generated where the filtrate was dropped, it could be judged that the bacteriophage that could kill E. coli cells was included in the filtrate. Through the above procedure, the filtrate containing the bacteriophage having the capability to kill E. coli cells could be obtained.

Then, the bacteriophage was isolated from the filtrate confirmed above to have the bacteriophage capable of killing E. coli cells. The conventional plaque assay was used for the bacteriophage isolation. Particularly, a plaque formed in the course of the plaque assay was picked up by using a sterilized tip, which was then added to the E. coli culture solution, followed by shaking culture at 37° C. for 4˜5 hours. Upon completion of the culture, centrifugation was performed at 8,000 rpm for 20 minutes to obtain supernatant. The recovered supernatant was inoculated with E. coli culture at the ratio of 1/50, followed by shaking culture at 37° C. for 3˜4 hours. To increase the titer of the bacteriophage, the above procedure was repeated at least 5 times. Then, centrifugation was performed at 8,000 rpm for 20 minutes to obtain supernatant. Plaque assay was performed with the obtained supernatant. In general, the pure bacteriophage isolation is not completed by one-time procedure, so the above procedure was repeated. At least 5 times of repeated procedure, the solution containing the pure bacteriophage was obtained. The procedure for the isolation of the pure bacteriophage is generally repeated until the generated plaques become similar in sizes and morphologies. And the final pure bacteriophage isolation was confirmed by the observation under electron microscope. Until the pure bacteriophage isolation was confirmed under electron microscope, the above procedure was repeated. The observation under electron microscope was performed by the conventional method. Briefly, the solution containing the pure bacteriophage was loaded on copper grid, followed by negative staining with 2% uranyl acetate. After drying thereof, the morphology was observed under transmission electron microscope. The electron micrograph of the bacteriophage isolated in the present invention is presented in FIG. 1. From the morphological observation, the bacteriophage isolated in the present invention was identified as belonging to the family Myoviridae.

The solution containing the pure bacteriophage confirmed above proceeded to purification. E. coli culture broth was added to the solution containing the pure bacteriophage at the volume of 1/50 of the total volume of the bacteriophage solution, followed by shaking culture at 37° C. for 3˜4 hours. Upon completion of the culture, centrifugation was performed at 8,000 rpm for 20 minutes to obtain supernatant. The said procedure was repeated 5 times to obtain a solution containing enough numbers of the bacteriophage. The supernatant obtained from the final centrifugation was filtered by a 0.45 μm filter, followed by the conventional polyethylene glycol (PEG) precipitation. Particularly, PEG and NaCl were added to 100 ml of the filtrate (10% PEG 8000/0.5 M NaCl), which stood at 4° C. for 2˜3 hours. Centrifugation was performed at 8,000 rpm for 30 minutes to obtain the bacteriophage precipitate. The obtained bacteriophage precipitate was resuspended in 5 ml of buffer (10 mM Tris-HCl, 10 mM MgSO₄, 0.1% Gelatin, pH 8.0). This solution was called the bacteriophage suspension or bacteriophage solution.

As a result, the purified pure bacteriophage was obtained, which was named as the bacteriophage EK88P-1 and then deposited at Korean Collection for Type Cultures, Korea Research Institute of Bioscience and Biotechnology in Apr. 10, 2014 (Accession No: KCTC 12574BP).

Example 2 Analysis of the Major Structural Proteins of the Isolated Bacteriophage

One-dimensional electrophoresis was performed to analyze the major structural proteins of the isolated bacteriophage. To obtain the proteins consisting the outer wall of the bacteriophage, 200 μl of the bacteriophage suspension prepared in Example 1 was mixed with 800 μl of acetone, which was vortexed vigorously. The mixture stood at −20° C. for 10 minutes. Centrifugation was performed at 13,000 rpm at 4° C. for 20 minutes to eliminate supernatant, followed by air drying. The precipitate was resuspended in 50 μl of electrophoresis sample buffer (5×), which was then boiled for 5 minutes. The prepared sample was analyzed by one-dimensional electrophoresis. As a result, as shown in FIG. 2, the major structural proteins in the sizes of approximately 49 kDa, 53 kDa, 94 kDa, and 103 kDa were confirmed.

Example 3 Separation of the Bacteriophage EK88P-1 Genome and Analyzing the Characteristics

The genome of the bacteriophage EK88P-1 was separated as follows. The genome was separated from the bacteriophage suspension obtained in Example 1. First, in order to eliminate DNA and RNA of E. coli host bacterial cells included in the suspension, DNase I and RNase A were added 200 U each to 10 and of the bacteriophage suspension, which was incubated at 37° C. for 30 minutes. 30 minutes later, to remove the DNase I and RNase A activity, 500 μl of 0.5 M ethylenediaminetetraacetic acid (EDTA) was added thereto, which was incubated for 10 minutes. The suspension was further incubated at 65° C. for 10 minutes and then added with 100 μl of proteinase K (20 mg/ml) to break the outer wall of the bacteriophage, followed by incubation at 37° C. for 20 minutes. 500 μl of 10% sodium dodecyl sulfate (SDS) solution was added thereto, followed by incubation at 65° C. for 1 hour. 10 ml and of the mixture of phenol:chloroform:isoamylalcohol (25:24:1) was added thereto, followed by mixing well. The mixture was centrifuged at 13,000 rpm for 15 minutes to separate each layer. The upper layer was obtained, to which isopropyl alcohol was added at the volume of 1.5 times the volume of the upper layer, followed by centrifugation at 13,000 rpm for 10 minutes to precipitate the genome of the bacteriophage. After collecting the precipitate, 70% ethanol was added to the precipitate, followed by centrifugation at 13,000 rpm for 10 minutes to wash the precipitate. The washed precipitate was vacuum-dried and then dissolved in 100 μl of water. The said procedure was repeated to obtain a sufficient amount of the bacteriophage EK88P-1 genome. The nucleotide sequence of the genome of the bacteriophage EK88P-1 obtained above was analyzed by Next Generation Sequencing (NGS) at National Instrumentation Center for Environmental Management, Seoul National University. Briefly, DNA fragment was fixed on the slide, followed by bridge amplification to form DNA fragment cluster. Then, SBS (Sequence by Synthesis), that was a nucleotide synthesis reaction, was performed by using the cluster as a template along with four different fluorescent-labeled nucleotides. This method is unique by the following characteristics: wherein DNA sequence is not amplified in a reaction solution like other methods but amplified on the slide where DNA is fixed with DNA bending to form sequence clusters. The formed cluster proceeded to sequencing group by group, and the obtained results were converted into each read sequence information, followed by analysis. 25 contigs in different sizes were obtained. The finally identified contig sequences of the bacteriophage EK88P-1 were presented by the nucleotide sequences of SEQ ID NO: 1 to SEQ ID NO: 25. These sequences were the partial nucleotide sequences that constitute the whole genomic sequence of the bacteriophage EK88P-1. The bacteriophage EK88P-1 was distinguished from others even with these partial nucleotide sequences.

Example 4 Analysis of the Characteristics of the Bacteriophage EK88P-1 Genome Using PCR

To disclose the characteristics of the genome of the bacteriophage EK88P-1, polymerase chain reaction (PCR) was performed. The primers used for the PCR were prepared by referring the partial nucleotide sequence represented by SEQ ID NO: 5. The primer information is listed in Table 1.

TABLE 1 Primer information PCR reaction Primer Sequence PCR 1 F-1 (SEQ. ID. TATCACCCATGTTCCACGCT NO: 26) R-1 (SEQ. ID. TGGTATTACTCGTCCGCAGT NO: 27) PCR 2 F-2 (SEQ. ID. CCAAGTGCCAGTCCTAAACG NO: 28) R-2 (SEQ. ID. ATGGGTCGGGTTACTGGTTC NO: 29) PCR 3 F-3 (SEQ. ID. ACCCAATCTCCTATTCTGTCCA NO: 30) R-3 (SEQ. ID. TGACTGATATTGATTCTGGCGA NO: 31) PCR 4 F-4 (SEQ. ID. GGTTTCAACTCGAGCAAGGG NO: 32) R-4 (SEQ. ID. TCGGTTGTATCTTGGGCTGA NO: 33) PCR 5 F-5 (SEQ. ID. CGGAATTTGTACATCACCGCT NO: 34) R-5 (SEQ. ID. CTTGATACGCAGGACCAAGC NO: 35)

PCR was performed by using the genome of the bacteriophage EK88P-1 prepared in Example 3 as a template with Maxime™ PCR PreMix Kit (i-Taq; Cat. No. 25026, iNtRON Biotechnology, Inc.) according to the manufacturer's protocol. GenePro PCR machine (BIOER) was used as a PCR machine. PCR was performed as follows; predenaturation at 94° C. for 10 minutes, denaturation at 94° C. for 1 minute, annealing at 56° C. for 30 seconds, polymerization at 72° C. for 1 minute seconds, 30 cycles from denaturation to polymerization, and final extension at 72° C. for 4 minutes. Then, the reaction mixture rested at 4° C. The PCR product was transferred onto 1.5% agarose gel for the conventional electrophoresis. The gel was observed by Molecular ImagerGelDoc™ XR+ (BIO-RAD).

The results of the PCR are presented in FIG. 3. An amplified PCR product in similar size to 834 bp which was the theoretical value was obtained from “PCR 1”. An amplified product in similar size to 885 bp which was the theoretical value was obtained from “PCR 2”. An amplified product in the size around 893 bp which was the theoretical value was obtained from “PCR 3” and an amplified produce in the size around 645 bp which was theoretical value was obtained from “PCR 4”. In the meantime, an amplified product in the size of about 562 bp which was the theoretical value was obtained from “PCR 5”. When the primers listed in Table 1 were used, the amplified products respectively in the sizes of 834 bp, 885 bp, 893 bp, 645 bp, and 562 bp were produced, which was the bacteriophage EK88P-1 specific characteristic. This characteristic alone could distinguish the bacteriophage EK88P-1 from previously reported bacteriophages.

Example 5 Investigation of E. coli Killing Ability of the Bacteriophage EK88P-1

The E. coli killing ability of the isolated bacteriophage EK88P-1 was investigated. To do so, the formation of clear zone was observed by the spot assay by the same manner as described in Example 1. Those E. coli strains used for the killing ability investigation were total 10 strains which had been isolated and identified as E. coli strains previously by the present inventors. Particularly, two of each strain of E. coli were used, which were two of E. coli K88 strains, two of E. coli K99 strains, two of E. coli 987P strains, two of E. coli F41 strains, and two of E. coli F18 strains. The bacteriophage EK88P-1 demonstrated E. coli killing ability to all the E. coli strains used in this experiment. The representative result of the E. coli killing ability test is shown in FIG. 4. In the meantime, the activity of the bacteriophage EK88P-1 to kill Enterococcus faecalis, Enterococcus faecium, Streptococcus mitis, Streptococcus uberis, and Staphylococcus aureus was also investigated. As a result, the bacteriophage EK88P-1 did not have the activity of killing these microorganisms.

Therefore, it was confirmed that the bacteriophage EK88P-1 had a broad antibacterial spectrum against E. coli, suggesting that the bacteriophage EK88P-1 of the present invention could be used as an active ingredient of a composition for the prevention and treatment of E. coli infections.

Example 6 Preventive Effect of Bacteriophage EK88P-1 on E. coli Infections

100 μl of the bacteriophage EK88P-1 solution (1×10⁹ pfu/ml) was added to a tube containing 9 ml of TSB. To another tube containing 9 ml of TSB, 100 μl of TSB was added. The E. coli culture was added to each tube to prepare bacterial suspension of OD₆₀₀=0.5. Then, the tubes were transferred in a 37° C. incubator, followed by shaking-culture, during which the growth of E. coli was observed. As presented in Table 2, the growth of E. coli was inhibited in the tube added with the bacteriophage EK88P-1 solution, while the growth of E. coli was not inhibited in the tube not added with the bacteriophage EK88P-1 solution.

TABLE 2 Inhibition of E. coli growth OD₆₀₀ 0 min. 15 min. 60 min. (−) bacteriophage 0.5 0.8 1.4 solution (+) bacteriophage 0.5 0.4 0.2 solution

The above results indicate that the bacteriophage EK88P-1 not only inhibits the growth of E. coli cells but also can kill the bacteria. Therefore, the bacteriophage EK88P-1 can be used as an active ingredient of a composition for preventing E. coli infections.

Example 7 Therapeutic Effect of Bacteriophage EK88P-1 on E. coli Infections

Therapeutic effect of the bacteriophage EK88P-1 on the pigs having E. coli infection was investigated. 4 weaning pigs at 25 days of age were grouped together; two groups of pigs were raised in a pig pen (1.1 m×1.0 m) for 14 days. Heating system was furnished and the surrounding environment was controlled. The temperature and the humidity of the pig pen were controlled and the floor was cleaned every day. On the 7^(th) day of the experiment, all the animals were orally administered with E. coli K88 cell suspension using an oral injection tube. The E. coli suspension administered above was prepared as follows: E. coli was cultured in TSB medium at 37° C. for 18 hours and the bacterial cells were collected by centrifugation. Saline (pH 7.2) was added to the bacterial cell pellet to make cell suspension at a centration of 10¹⁰ CFU/ml. From the next day of the E. coli challenge, the experimental group pigs were orally administered with the bacteriophage EK88P-1 (10⁹ PFU/pig) via the same way as used for the above administration twice a day. The control group pigs (bacteriophage solution non-treated pigs) were treated with nothing. Feeds and drinking water were equally provided to both groups. After the challenge of E. coli, all the animals were observed every day whether or not they experienced diarrhea. The observation was performed by measuring the diarrhea index. The diarrhea index was set as follows according to Fecal Consistency (FC) score (normal: 0, loose stool: 1, moderate diarrhea: 2, and severe diarrhea: 3). The results are shown in Table 3.

TABLE 3 Fecal Consistency score Days after E. coli challenge 0 1 2 3 4 5 6 Control group (− 1.0 1.5 1.5 1.25 1.0 1.0 1.0 bacteriophage solution) Experimental group (+ 1.0 0.5 0.25 0.25 0 0 0 bacteriophage solution)

From the above results, it was confirmed that the bacteriophage EK88P-1 of the present invention could be very effective to treat E. coli infections.

Example 8 Preparation of Feed Additives and Feeds

Feed additive containing bacteriophage at a concentration of 1×10⁹ pfu/g was prepared using the bacteriophage EK88P-1 solution. The preparation method thereof was as follows: Maltodextrin (40 weight %) and trehalose (10 weight %) were added to the bacteriophage solution. After mixing well, the mixture was freeze-dried. Lastly, the dried mixture was grinded into fine powders. The drying process above can be replaced with vacuum-drying, drying at warm temperature, or drying at room temperature. To prepare the control feed additive for comparison, feed additive that did not contain the bacteriophage but contain buffer (10 mM Tris-HCl, 10 mM MgSO₄, 0.1% Gelatin, pH 8.0) only were prepared.

The above two kinds of feed additives were mixed with feed at the volume of 1000 times the volume of feed additive respectively, resulting in two kinds of final feeds.

Example 9 Preparation of Drinking Water Additives and Disinfectants

Drinking water additive and disinfectant are different in intended use but same in the composition, so they have been prepared by the same manner. Drinking water additive (or disinfectant) containing bacteriophage at a concentration of 1×10⁹ pfu/ml was prepared using the bacteriophage EK88P-1 solution. Particularly, to prepare drinking water additive or disinfectant, the bacteriophage EK88P-1 solution was added to buffer solution which is 1×10⁹/ml, which was well mixed. For the comparison, the above buffer solution itself was used as the drinking water additive (or disinfectant) that did not contain the bacteriophage.

The prepared two kinds of drinking water additives (or disinfectants) were diluted in water at the ratio of 1:1,000, and then used as drinking water or disinfectant.

Example 10 Effect on Pig Farming

The effect of the feeds, drinking water, and disinfectant prepared in Example 8 and Example 9 on pig farming was investigated. Particularly, the investigation was focused on mortality. Total 30 pigs were grouped into three groups, and each group was composed of 10 pigs (group A: fed with the feeds of the present invention, group B: provided with the drinking water of the present invention; and group C: treated with the disinfectant of the present invention). The experiment was continued for 4 weeks. Each group was divided by two sub-groups comprising 5 pigs each. The sub-groups were divided according to the treatment of the bacteriophage EK88P-1 or not (sub-group-{circle around (1)}: treated with the bacteriophage EK88P-1; and sub-group-{circle around (2)}: not-treated with the bacteriophage EK88P-1). The pigs used in this experiment were weaning pigs at the age of 20 days. The pigs in each sub-group were separated each other and raised in a separated room placed at a sufficient distance from each other. Each sub-group was divided and named as shown in Table 4.

TABLE 4 Sub-groups of pig farming experiment Sub-group Treated with the Not-treated with bacteriophage the bacteriophage EK88P-1 EK88P-1 Fed with feeds A-{circle around (1)} A-{circle around (2)} Provided with B-{circle around (1)} B-{circle around (2)} drinking water Treated with C-{circle around (1)} C-{circle around (2)} disinfectant

Feeds were provided according to the conventional feed supply method as presented in Table 4 with the feeds prepared in Example 8. Drinking water was provided according to the conventional water supply method as presented in Table 4 with the drinking water prepared in Example 9. Disinfectant was treated to the pigs three times a week with taking turns with the conventional disinfectant. That is, on the day when the disinfectant of the present invention was sprayed, the conventional disinfectant was not treated. The results are shown in Table 5.

TABLE 5 Group Mortality (%) A-{circle around (1)} 0 A-{circle around (2)} 20 B-{circle around (1)} 0 B-{circle around (2)} 40 C-{circle around (1)} 0 C-{circle around (2)} 40

From the above results, it was confirmed that the feeds, drinking water, and the disinfectant prepared according to the present invention were effective in reducing the pig mortality. Therefore, it can be concluded that the composition of the present invention can be efficiently applied for the improvement of productivity of pig farming.

Those skilled in the art will appreciate that the conceptions and specific embodiments disclosed in the foregoing description may be readily utilized as a basis for modifying or designing other embodiments for carrying out the same purposes of the present invention. Those skilled in the art will also appreciate that such equivalent embodiments do not depart from the spirit and scope of the invention as set forth in the appended Claims. 

What is claimed is:
 1. A method of treating or reducing mortality due to E. coli diarrhoea in a non-human animal subject, the method comprising the step of spraying on the non-human animal subject or administering orally to the non-human animal subject a composition comprising as the active ingredient an effective concentration of the isolated bacteriophage EK88P-1 having the genome composed of nucleotide sequences set forth in SEQ ID NO: 1 to SEQ ID NO: 25, wherein the bacteriophage EK88P-1 has a broad antibacterial spectrum against E. coli and is deposited under the accession number KCTC 12574BP.
 2. The method of claim 1, wherein the composition is sprayed on the non-human animal subject in the form of disinfectant.
 3. The method of claim 1, wherein the composition is orally administered to the non-human animal subject in the form of a feed additive or drinking water.
 4. The method of claim 1, wherein the non-human animal subject is a pig. 